TECHNICAL FIELD
[0001] The present invention relates to an internal combustion engine and a vehicle.
BACKGROUND ART
[0002] There are conventional internal combustion engines that have a valve mechanism including:
a circular columnar-shaped support member that is inserted into a hole formed in a
cylinder head; a rocker arm that is pivotally supported on the support member; and
a cam that is provided on a cam shaft and is in contact with the rocker arm. Patent
Document No. 1 discloses a valve mechanism that includes a lash adjuster as the support
member.
CITATION LIST
PATENT LITERATURE
[0003] Patent Document No. 1: Japanese Laid-Open Patent Publication No.
2009-185753
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0004] In the valve mechanism, the rocker arm is held down by the cam. Therefore, the support
member is held down by the cam with the rocker arm therebetween. However, the support
member is only inserted into the hole of the cylinder head and is not particularly
secured to the cylinder head. While the internal combustion engine is running, a load
in the axial direction of the support member is repeatedly generated on the support
member. Therefore, the support member may possibly rise from the hole, leading to
problems such as fretting wear. On the other hand, if the support member is secured
to the cylinder head using screws in order to prevent the rise, it will detract from
the ease of installment of the support member.
[0005] The present invention has been made in view of the above, and an object thereof is
to provide an internal combustion engine that allows a support member to be installed
easily while preventing fretting wear, or the like, due to rising of the support member,
and a vehicle having the same.
SOLUTION TO PROBLEM
[0006] An internal combustion engine according to the present invention includes: a cylinder
member formed with a hole; a port formed in the cylinder member; a valve installed
in the cylinder member that opens/closes the port; a cam shaft rotatably supported
on the cylinder member; a cam provided on the cam shaft; a columnar support member
at least a portion of which is inserted into the hole of the cylinder member; a rocker
arm that includes a supported portion pivotally supported on the support member, a
pressed portion pressed by the cam, and an abutting portion to abut on the valve;
and a securing member that secures the support member inside the hole. The securing
member includes a first contact portion to be in contact with the support member,
a second contact portion to be in contact with the cylinder member, and an elastic
portion interposed between the first contact portion and the second contact portion.
[0007] With the internal combustion engine described above, when the support member is pushed
into the hole of the cylinder member, the support member is inserted into the hole.
The support member is inserted into the hole and is then secured inside the hole by
the elastic force of the elastic portion of the securing member. With the internal
combustion engine described above, there is no need for an operation of securing the
support member to the cylinder member by using screws. This makes the installment
of the support member easy. Since the support member is secured by the elastic force
of the elastic portion of the securing member, it is possible to prevent the support
member from rising from the hole. Therefore, with the internal combustion engine described
above, it is possible to prevent fretting wear, or the like, due to rising of the
support member while maintaining the ease of installment of the support member.
[0008] According to one preferred embodiment of the present invention, the securing member
is a plunger mechanism that includes a spring arranged inside the support member,
and a presser at least a portion of which is arranged outside the support member and
that is connected to the spring.
[0009] According to the embodiment described above, the securing member can be configured
to be simple and compact. By appropriately setting the spring constant, etc., of the
spring, the ease of operation of inserting the support member into the hole and the
prevention of rising of the support member can be realized in a well-balanced manner.
[0010] According to one preferred embodiment of the present invention, the securing member
is a snap ring that is fitted to the support member.
[0011] According to the embodiment described above, the securing member can be configured
to be simple and compact.
[0012] According to one preferred embodiment of the present invention, the securing member
is a ring-shaped coil spring that is wound around the support member.
[0013] According to the embodiment described above, the securing member can be configured
to be simple and compact.
[0014] According to one preferred embodiment of the present invention, a groove that engages
with the securing member is formed on an inner surface of the hole of the cylinder
member.
[0015] According to the embodiment described above, when the support member is inserted
into the hole of the cylinder member, the securing member engages with the groove,
thus securing the support member inside the hole. As the securing member engages with
the groove, the support member is even less likely to rise. Therefore, the ease of
installment of the support member and the prevention of fretting wear, or the like,
due to rising of the support member can be both realized at a high level.
[0016] According to one preferred embodiment of the present invention, in a cross-section
that passes through a part of the groove and that includes a center line of the hole,
the groove has a sloped surface that is inclined relative to the center line of the
hole so as to come closer to the center line of the hole while extending toward the
rocker arm along a direction of the center line of the hole.
[0017] According to the embodiment described above, the support member is even less likely
to rise. Therefore, it is possible to even better prevent fretting wear, or the like,
due to rising of the support member.
[0018] According to one preferred embodiment of the present invention, the groove is a cone-shaped
or circular columnar-shaped groove having an axis that is inclined relative to the
center line of the hole.
[0019] According to the embodiment described above, the groove can be machined by inserting
a tool such as a drill or an endmill into the hole of the cylinder member from outside
in a direction that is slanted relative to the center line of the hole. Therefore,
the groove can be formed in a simple and inexpensive manner.
[0020] According to one preferred embodiment of the present invention, the hole and the
support member are each formed in a circular columnar shape. The groove is a circumferential
groove formed on an inner circumferential surface of the hole.
[0021] Where the groove is formed only at one point in the circumferential direction of
the hole, if the position at which the groove is machined is shifted in the circumferential
direction, the position at which the support member is attached in the circumferential
direction may possibly be shifted. However, according to the embodiment described
above, since the groove is formed in a circumferential pattern, the position at which
the support member is attached in the circumferential direction is prevented from
being shifted. Therefore, even if the machining precision of the groove is relatively
low, it is possible to properly machine the groove. Thus, the groove can be formed
in a simple and inexpensive manner.
[0022] According to one preferred embodiment of the present invention, the securing member
is a plunger mechanism that includes a spring arranged inside the cylinder member,
and a presser at least a portion of which is arranged inside the hole of the cylinder
member and that is connected to the spring.
[0023] According to the embodiment described above, it is possible to increase the degree
of freedom in the position of installing of the securing member. By appropriately
setting the spring constant, etc., of the spring, the ease of operation of inserting
the support member into the hole and the prevention of rising of the support member
can be realized in a well-balanced manner.
[0024] According to one preferred embodiment of the present invention, the securing member
is a snap ring that is fitted to an inner surface of the hole of the cylinder member.
[0025] According to the embodiment described above, the securing member can be configured
to be simple and compact.
[0026] According to one preferred embodiment of the present invention, the securing member
is a ring-shaped coil spring that is fitted to an inner surface of the hole of the
cylinder member.
[0027] According to the embodiment described above, the securing member can be configured
to be simple and compact.
[0028] According to one preferred embodiment of the present invention, the securing member
is a leaf spring that is secured to an edge of the hole of the cylinder member.
[0029] According to the embodiment described above, the securing member can be configured
to be simple.
[0030] According to one preferred embodiment of the present invention, the rocker arm includes
a first arm that includes the supported portion and the abutting portion, and a second
arm that includes the pressed portion and is pivotally supported on the first arm.
The internal combustion engine includes a connecting mechanism that removably connects
the first arm and the second arm. The support member is configured to be unable to
expand/contract in an axial direction of the support member.
[0031] Where the rocker arm includes the second arm that is pivotally supported on the first
arm, and the support member is a member that can contract/expand in the axial direction,
such as a lash adjuster, the relative position between the first arm and the second
arm may possibly be shifted following the expansion/contraction of the support member
when the connection between the first arm and the second arm is disconnected. As a
result, the second arm may be shifted from the intended position relative to the first
arm, and the connecting mechanism may fail to properly connect the first arm and the
second arm. However, according to the embodiment described above, since the support
member is unable to expand/contract in the axial direction, it is possible to prevent
the lowering of the connection function.
[0032] A vehicle according to the present invention includes the internal combustion engine
described above.
[0033] Thus, it is possible to obtain a vehicle that realizes the advantageous effects described
above.
ADVANTAGEOUS EFFECTS OF INVENTION
[0034] According to the present invention, it is possible to provide an internal combustion
engine that allows easy installment of a support member that supports a rocker arm
while preventing fretting wear, or the like, due to rising of the support member,
and a vehicle having the same.
BRIEF DESCRIPTION OF DRAWINGS
[0035]
FIG. 1 is a view showing an example of an internal combustion engine according to one embodiment
of the present invention installed in an automobile.
FIG. 2 is a partial cross-sectional view of the internal combustion engine.
FIG. 3 is a partial enlarged cross-sectional view of the internal combustion engine.
FIG. 4 is a side view of a rocker arm and a support member.
FIG. 5 is a plan view of the rocker arm and the support member.
FIG. 6 is an exploded perspective view of a first arm and a second arm of the rocker arm.
FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 4.
FIG. 8 is equivalent to FIG. 7, showing the rocker arm in the connected state.
FIG. 9 is a side view showing the rocker arm in the connected state that has pivoted relative
to the support member.
FIG. 10 is equivalent to FIG. 7, showing the rocker arm when the second arm pivots relative to the first arm.
FIG. 11 is a side view showing the rocker arm and the support member when the second arm
pivots relative to the first arm.
FIG. 12A is a side view of a support member.
FIG. 12B is a cross-sectional view taken along line XIIb-XIIb of FIG. 12A.
FIG. 13 is a cross-sectional view of a hole of a cylinder head.
FIG. 14 is a side view of a support member according to an alternative embodiment.
FIG. 15A is a cross-sectional view of a support member according to an alternative embodiment.
FIG. 15B is a cross-sectional view taken along line XVb-XVb of FIG. 15A.
FIG. 16 is a cross-sectional view of a support member according to an alternative embodiment.
FIG. 17A is a cross-sectional view of a support member according to an alternative embodiment.
FIG. 17B is a cross-sectional view taken along line XVIIb-XVIIb of FIG. 17A.
FIG. 18 is a cross-sectional view of a support member according to an alternative embodiment.
FIG. 19 is a side view of a support member according to an alternative embodiment.
DESCRIPTION OF EMBODIMENTS
[0036] An embodiment of the present invention will now be described with reference to the
drawings. An internal combustion engine according to the present embodiment is installed
in a vehicle and used as the drive source of the vehicle. There is no limitation on
the type of the vehicle, which may be a straddled vehicle such as a motorcycle, an
auto tricycle or an ATV (All Terrain Vehicle) or may be an automobile. For example,
an internal combustion engine
10 may be arranged in the engine room of an automobile
5 as shown in FIG.
1.
[0037] The internal combustion engine
10 according to the present embodiment is a multi-cylinder engine having a plurality
of cylinders. The internal combustion engine
10 is a 4-stroke engine that goes through the intake stroke, the compression stroke,
the combustion stroke and the exhaust stroke. FIG.
2 is a partial cross-sectional view of the internal combustion engine
10. As shown in FIG.
2, the internal combustion engine
10 includes a crankcase (not shown), a cylinder body
7 connected to the crankcase, and a cylinder head
12 connected to the cylinder body
7. A crankshaft (not shown) is arranged inside the crankcase. A plurality of cylinders
6 are provided inside the cylinder body
7. A piston
8 is arranged inside each cylinder
6. The piston
8 and the crankshaft are connected by a connecting rod (not shown).
[0038] An intake cam shaft
23 and an exhaust cam shaft
21 are rotatably supported on the cylinder head
12. Intake cams
23A are provided on the intake cam shaft
23, and exhaust cams
21A are provided on the exhaust cam shaft
21.
[0039] Intake ports
16 and exhaust ports
14 are formed in the cylinder head
12. An intake opening
18 is formed at one end of the intake port
16. An exhaust opening
17 is formed on one end of the exhaust port
14. The intake port
16 communicates with a combustion chamber
15 through the intake opening
18. The exhaust port
14 communicates with the combustion chamber
15 through the exhaust opening
17. The intake port
16 serves to guide the mixed gas of the air and the fuel into the combustion chamber
15. The exhaust port
14 serves to guide the exhaust gas discharged from the combustion chamber
15 to the outside.
[0040] Intake valves
22 and exhaust valves
20 are installed in the cylinder head
12. The intake valve
22 opens/closes the intake opening
18 of the intake port
16. The exhaust valve
20 opens/closes the exhaust opening
17 of the exhaust port
14. The intake valve
22 and the exhaust valve
20 are so-called poppet valves. The intake valve
22 has a shaft portion
22a and an umbrella portion
22b, and the exhaust valve
20 has a shaft portion
20a and an umbrella portion
20b. The configuration of the intake valve
22 and the configuration of the exhaust valve
20 are similar to each other, and the configuration of the intake valve
22 will be described below while omitting the description of the configuration of the
exhaust valve
20. The shaft portion
22a of the intake valve
22 is slidably supported on the cylinder head
12 with a cylinder-shaped sleeve
24 therebetween. A valve stem seal
25 is attached to one end of the sleeve
24 and the shaft portion
22a of the intake valve
22. The shaft portion
22a of the intake valve
22 extends through the sleeve
24 and the valve stem seal
25. A tappet
26 is fitted to the tip of the shaft portion
22a.
[0041] As shown in FIG.
3, a cotter
28 is attached to the shaft portion
22a of the intake valve
22. The cotter
28 is fitted to a valve spring retainer
30. The valve spring retainer
30 is secured to the intake valve
22 with the cotter
28 therebetween. The valve spring retainer
30 can move, together with the intake valve
22, in an axial direction of the intake valve
22. The intake valve
22 extends through the valve spring retainer
30.
[0042] The internal combustion engine
10 includes a valve spring
32 that provides the intake valve
22 with a force in the direction of closing the intake opening
18 (the upward direction in FIG.
3). The valve spring
32 is a compression coil spring, and includes a first spring end portion
32a supported on the valve spring retainer
30 and a second spring end portion
32b supported on the cylinder head
12.
[0043] The internal combustion engine
10 includes a rocker arm
40 that receives a force from the intake cam
23A to open/close the intake valve
22. The rocker arm
40 is pivotally supported on the cylinder head
12 with a support member
35 therebetween. FIG.
4 is a side view of the rocker arm
40 and the support member
35, and FIG.
5 is a plan view of the rocker arm
40 and the support member
35. The rocker arm
40 includes a first arm
41 and a second arm
42 including a roller
43.
[0044] FIG.
6 is an exploded perspective view of the first arm
41 and the second arm
42. The first arm
41 includes a plate
41A, a plate
41B, an abutting plate
41C and a connecting plate
41D. The plate
41A and the plate
41B are arranged parallel to each other. The abutting plate
41C and the connecting plate
41D cross the plate
41A and the plate
41B. The abutting plate
41C and the connecting plate
41D connect together the plate
41A and the plate
41B. The plate
41A is formed with a hole
46A and a hole
48. The plate
41B is formed with a hole
46B (see FIG.
7) and the hole
48. The holes
46A,
46B and
48 extend in the direction parallel to the axial line direction of the intake cam shaft
23 (see FIG.
3).
[0045] FIG.
7 is a cross-sectional view taken along line VII-VII of FIG.
4. As shown in FIG.
7, a cylinder-shaped boss portion
49A is provided around the hole
46A of the plate
41A. A connecting pin
60A is slidably inserted inside the hole
46A. A bottomed cylinder-shaped cover portion
49B is provided around the hole
46B of the plate
41B. The cover portion
49B is provided with a hole
47 having a smaller diameter than the hole
46B, but the hole
47 may be omitted. A connecting pin
60B is slidably inserted inside the hole
46B. A spring
64 is arranged inside the hole
46B. The spring
64 is present between the cover portion
49B and the connecting pin
60B, and urges the connecting pin
60B toward the plate
41A.
[0046] The second arm
42 is arranged on the inner side of the first arm
41. That is, the second arm
42 is arranged between the plate
41A and the plate
41B. As shown in FIG.
6 the second arm
42 includes a plate
42A, a plate
42B, an abutting plate
42C and a connecting plate
42D. The plate
42A and the plate
42B are arranged parallel to each other. The abutting plate
42C and the connecting plate
42D cross the plate
42A and the plate
42B. The abutting plate
42C and the connecting plate
42D connect together the plate
42A and the plate
42B. The plate
42A and the plate
42B are formed with a hole
50 and a hole
52, respectively.
[0047] As shown in FIG.
7, the cylinder-shaped roller
43 is rotatably supported on the hole
50 of the plate
42A and the hole
50 of the plate
42B. Specifically, a cylinder-shaped collar
54 is inserted through the holes
50 of the plate
42A and the plate
42B. The roller
43 is rotatably supported on the collar
54. A connecting pin
62 is slidably inserted inside the collar
54. Since the collar
54 is arranged inside the holes
50, the connecting pin
62 is slidably inserted inside the holes
50. Note that the collar
54 is not always necessary. The connecting pin
62 may rotatably support the roller
43.
[0048] An outer diameter of the connecting pin
60B is less than or equal to an inner diameter of the collar
54. The connecting pin
60B is formed so that it can be inserted inside the collar
54. An outer diameter of the connecting pin
62 is less than or equal to an inner diameter of the hole
46A. The connecting pin
62 is formed so that it can be inserted inside the hole
46A. In the present embodiment, the inner diameter of the collar
54 and the inner diameter of the hole
46A are equal to each other. The outer diameter of the connecting pin
60B, the outer diameter of the connecting pin
62 and an outer diameter of the connecting pin
60A are equal to each other.
[0049] As shown in FIG.
4, the support member
35, the first arm
41 and the second arm
42 are connected together by a support pin
56. The support pin
56 is inserted through the hole
48 of the plate
41A and the hole
48 of the plate
41B of the first arm
41, and the hole
52 of the plate
42A and the hole
52 of the plate
42B of the second arm
42. The first arm
41 and the second arm
42 are pivotally supported on the support member
35 by the support pin
56. The second arm
42 is pivotally supported on the first arm
41 by the support pin
56.
[0050] As shown in FIG.
7, a connection switch pin
66 is arranged on the side of the rocker arm
40. The connection switch pin
66 is configured to be movable in the direction toward the connecting pin
60A and in the direction away from the connecting pin
60A.
[0051] As shown in FIG.
8, when the connection switch pin
66 moves in the direction away from the connecting pin
60A, the connecting pins
60A,
62 and
60B slide leftward in FIG.
8 due to the force of the spring
64. Thus, the connecting pin
60B is located inside the hole
46B and inside the hole
50 (specifically, inside the collar
54), and the connecting pin
62 is located inside the hole
50 (specifically, inside the collar
54) and inside the hole
46A. This state will hereinafter be referred to as the connected state. In the connected
state, the first arm
41 and the second arm
42 are connected together by the connecting pin
60B and the connecting pin
62. As a result, as shown in FIG.
9, the first arm
41 and the second arm
42 are, as a single unit, pivotable about the axis of the support pin
9.
[0052] As shown in FIG.
7, the connection switch pin
66 moves toward the connecting pin
60A, the connecting pins
60A,
62 and
60B are pushed by the connection switch pin
66 and slide rightward in FIG.
7. Thus, the connecting pin
60B is located inside the hole
46B and not located inside the hole
50, and the connecting pin
62 is located inside the hole
50 and not located inside the hole
46A. This state will hereinafter be referred to as the non-connected state. In the non-connected
state, as shown in FIG.
10, the connecting pin
62 is slidable relative to the connecting pin
60A and the connecting pin
60B. As a result, as shown in FIG.
11, the second arm
42 is pivotable about the axis of the support pin
56 relative to the first arm
41. Therefore, the second arm
42 pivots about the axis of the support pin
56 while the first arm
41 does not pivot.
[0053] As shown in FIG.
3, the portion of the first arm
41 that is supported by the support pin
56 (specifically, the portion of the plate
41A around the hole
48 and the portion of the plate
41B around the hole
48) forms a supported portion
41S that is pivotally supported on the cylinder head
12. The abutting plate
41C forms an "abutting portion" that is to abut on the intake valve
22 with the tappet
26 therebetween. The roller
43 forms a "pressed portion" that is in contact with the intake cam
23A and is pressed by the intake cam
23A.
[0054] As shown in FIG.
3, the support member
35 that pivotally supports the rocker arm
40 is inserted into a hole
37 formed in the cylinder head
12. In the present embodiment, the cylinder head
12 corresponds to the "cylinder member". Note, however, that a cam carrier (not shown)
may be attached to the cylinder head
12, and the hole
37, through which the support member
35 is inserted, may be formed in the cam carrier. In such a case, the cylinder head
12 and the cam carrier, combined together, correspond to the "cylinder member". Thus,
another member may be attached to the cylinder head
12, and the hole
37 may be formed in that member. In such a case, the cylinder head
12 and the other member, combined together, correspond to the "cylinder member". In
the present embodiment, the support member
35 is formed in a circular columnar shape. Note however that the support member
35 is not limited to a circular columnar shape, but may be a polygonal columnar shape,
for example, or any other columnar shape. The hole
37 preferably has a cross-sectional shape that corresponds to the cross-sectional shape
of the support member
35.
[0055] FIG.
12A is a side view of the support member
35. FIG.
12B is a cross-sectional view taken along line XIIb-XIIb of FIG.
12A. As shown in FIG.
12A, the support member
35 includes a shaft portion
35A at least a portion of which is inserted into the hole
37, and a ring portion
35B formed with a hole
35C through which the support pin
56 (see FIG.
3) is inserted. A ball plunger
39 is provided inside the shaft portion
35A as a securing member that secures the support member
35 in the hole
37.
[0056] As shown in FIG.
12B, the shaft portion
35A of the support member
35 is formed with a hole
35D extending in the radial direction. The ball plunger
39 is fitted in the hole
35D. The ball plunger
39 includes a spring
39A that is a compression coil spring, a spring seat
39B that is connected to one end of the spring
39A, and a ball
39C that is connected to the other end of the spring
39A. While the ball
39C is an example of a presser of a plunger mechanism, the presser is not limited to
the ball
39C but may be a pin, etc. A portion of the ball
39C is exposed on the outside of the hole
35D. The inner circumferential surface of the hole
37 of the cylinder head
12 is formed with a groove
37a that engages with the ball
39C.
[0057] Although there is no limitation on the shape of the groove
37a, the groove
37a has a sloped surface
37b as shown in FIG.
13 in the present embodiment. As shown in FIG.
13, in a cross-section that passes through a part of the groove
37a and that includes a center line
37c of the hole
37, the sloped surface
37b is inclined relative to the center line
37c so as to come closer to the center line
37c while extending toward the rocker arm
40 along the direction of the center line
37c of the hole
37 (i.e., upward in FIG.
13).
[0058] The groove
37a is a cone-shaped or circular columnar-shaped groove having an axis
13c that is inclined relative to the center line
37c of the hole
37. The groove
37a according to the present embodiment can be easily machined by inserting a tool
13 such as a drill or an endmill into the hole
37 in a direction that is slanted relative to the center line
37c.
[0059] With the internal combustion engine
10 according to the present embodiment, the support member
35 is not screwed onto the cylinder head
12. The support member
35 can be easily attached to the cylinder head
12 by inserting the support member
35 into the hole
37. Specifically, by positioning the shaft portion
35A of the support member
35 above the hole
37 and inserting the shaft portion
35A into the hole
37, the ball
39C is pushed by the inner circumferential surface of the hole
37, thus compressing the spring
39A. When the shaft portion
35A is inserted to a predetermined position, the ball
39C engages with the groove
37a. Then, the operator feels a clicking sensation and thus easily knows that the shaft
portion
35A has been inserted to a predetermined position. Therefore, the support member
35 can be easily positioned, and the support member
35 is unlikely to come out of the hole
37. With the elastic force generated by the compression of the spring
39A, the ball
39C is pressed against the inner circumferential surface of the hole
37. The pressure with which the ball
39C presses the inner circumferential surface of the hole
37 secures the support member
35 inside the hole
37.
[0060] Note that in the present embodiment, the spring seat
39B is an example of the first contact portion in contact with the support member
35. The ball
39C is an example of the second contact portion in contact with the cylinder head
12. The spring
39A is present between the spring seat
39B and the ball
39C, and is an example of the elastic portion.
[0061] As shown in FIG.
3, the internal combustion engine
10 includes a compression coil spring
68, as a lost motion spring, that urges the rocker arm
40 toward the intake cam
23A. A shaft
70 that extends along a winding axis
68d of the compression coil spring
68 is arranged inside the compression coil spring
68. The shaft
70 has a first end portion
70a, and a second end portion
70b that is arranged on the second arm
42 side relative to the first end portion
70a. A spring seat
72 that receives the compression coil spring
68 is provided at the first end portion
70a.
[0062] The compression coil spring
68 has a first end portion
68a, and a second end portion
68b that is arranged on the second arm
42 side relative to the first end portion
68a. A retainer
74 is supported at the second end portion
68b. The retainer
74 includes a disc-shaped top plate portion
74a and a cylinder-shaped tube portion
74b. The tube portion
74b extends from the top plate portion
74a along the axial direction of the shaft
70 toward the compression coil spring
68. The top plate portion
74a is supported on the second end portion
68b of the compression coil spring
68. The top plate portion
74a is in contact with the abutting plate
42C of the second arm
42 of the rocker arm
40.
[0063] The spring seat
72, at least a portion of the shaft
70, at least a portion of the compression coil spring
68 and at least a portion of the tube portion
74b of the retainer
74 are arranged inside a hole
76 formed in the cylinder head
12.
[0064] The intake valve
22, the valve spring
32, the shaft
70, the retainer
74, the compression coil spring
68 and the support member
35 are arranged parallel to each other. The retainer
74 is arranged between the valve spring
32 and the support member
35. The shaft
70 is arranged between the valve spring
32 and the support member
35.
[0065] As shown in FIG.
2, as with the intake valve
22, the valve spring
32, the valve spring retainer
30, the rocker arm
40, the support member
35, the compression coil spring
68, etc., are provided also for the exhaust valve
20. These elements are similar to those described above, and will not be described in
detail below.
[0066] With the internal combustion engine
10 according to the present embodiment, it is possible to switch the operation state
of the intake valve
22 and the exhaust valve
20 by switching the state of the connection switch pin
66.
[0067] That is, when the connection switch pin
66 is switched to the connected state, the first arm
41 and the second arm
42 of the rocker arm
40 are connected together by the connecting pin
60B and the connecting pin
62 (see FIG.
8). When the intake cam
23A pushes the roller
43 of the rocker arm
40 following the rotation of the intake cam shaft
23, the first arm
41 and the second arm
42, as a single unit, pivot about the axis of the support pin
56 (see FIG.
9). As a result, the abutting plate
41C of the first arm
41 pushes the intake valve
22, thus opening the intake opening
18 of the intake port
16. Similarly, when the exhaust cam
21A pushes the roller
43 of the rocker arm
40 following the rotation of the exhaust cam shaft
21, the first arm
41 and the second arm
42, as a single unit, pivot about the axis of the support pin
56. As a result, the abutting plate
41C of the first arm
41 pushes the exhaust valve
20, thus opening the exhaust opening
17 of the exhaust port
14.
[0068] When the connection switch pin
66 is switched to the non-connected state, the connection between the first arm
41 and the second arm
42 by the connecting pin
60B and the connecting pin
62 is disconnected (see FIG.
7). The second arm
42 becomes pivotable relative to the first arm
41 (see FIG.
10). When the intake cam
23A pushes the roller
43 following the rotation of the intake cam shaft
23, the second arm
42 pivots about the axis of the support pin
56 while the first arm
41 does not pivot (see FIG.
11). Therefore, the abutting plate
41C of the first arm
41 will not push the intake valve
22, and the intake opening
18 remains closed by the intake valve
22. Similarly, when the exhaust cam
21A pushes the roller
43 following the rotation of the exhaust cam shaft
21, the second arm
42 pivots about the axis of the support pin
56 while the first arm
41 does not pivot. Therefore, the abutting plate
41C of the first arm
41 will not push the exhaust valve
20, and the exhaust opening
17 remains closed by the exhaust valve
20. Thus, in the present embodiment, one or more of a plurality of cylinders can be brought
to the inoperative state by switching the connection switch pin
66 to the non-connected state. For example, by making one or more cylinders inoperative
while the load is small, it is possible to improve the fuel efficiency.
[0069] As described above, with the internal combustion engine
10 according to the present embodiment, the support member
35 that pivotally supports the rocker arm
40 is not only inserted into the hole
37 of the cylinder head
12 but is also secured inside the hole
37 by the ball plunger
39. While the internal combustion engine
10 is running, the cam
21A,
23A repeatedly presses the rocker arm
40, and a load in the axial direction is repeatedly generated on the support member
35. However, since the support member
35 is secured inside the hole
37 by the ball plunger
39, it is possible to prevent the support member
35 from rising from the hole
37. Therefore, it is possible to prevent fretting wear, or the like, due to rising of
the support member
35.
[0070] With the internal combustion engine
10, when the support member
35 is pushed into the hole
37, the support member
35 is inserted into the hole
37 and is then secured inside the hole
37 by the elastic force of the spring
39A of the ball plunger
39. With the internal combustion engine
10 according to the present embodiment, there is no need for an operation of securing
the support member
35 to the cylinder head
12 by using screws, bolts, or the like. This makes the installment of the support member
35 easy.
[0071] Thus, with the internal combustion engine
10 according to the present embodiment, it is possible to prevent fretting wear, or
the like, due to rising of the support member
35 while maintaining the ease of installment of the support member
35.
[0072] Now, where the support member
35 is a member that can contract/expand in the axial direction, such as a lash adjuster,
the position of the rocker arm
40 changes following the contraction/expansion of the support member
35. For example, when the support member
35 expands, the rocker arm
40 moves toward the cam
21A,
23A (upward in FIG.
3). As a result, the position of the pivot center of the second arm
42 moves toward the cam
21A,
23A. On the other hand, since the position of the cam
21A,
23A does not change, the contact position between the roller
43 and the cam
21A,
23A does not change. Therefore, if the support member
35 expands when the rocker arm
40 is in the non-connected state, the second arm
42 may not be able to return to the position where the hole
50 and the hole
46A,
46B are aligned with each other (the position shown in FIG.
7). Then, it is possible that the first arm
41 and the second arm
42 may not be properly connected together by the connecting pin
60B and the connecting pin
62, and the connecting function of the rocker arm
40 may possibly lower. However, in the present embodiment, the support member
35, as opposed to a lash adjuster, cannot expand/contract in the axial direction. The
rocker arm
40 does not move toward the cam
21A,
23A. Therefore, it is possible to prevent the lowering of the connecting function of the
first arm
41 and the second arm
42 of the rocker arm
40.
[0073] Although there is no limitation on the securing member for securing the support member
35 inside the hole
37 of the cylinder head
12, the present embodiment comprises the ball plunger
39, which includes the spring
39A arranged inside the support member
35, and the ball
39C at least a portion of which is arranged outside the support member
35. Therefore, the securing member can be configured to be simple and compact. By appropriately
setting the spring constant, etc., of the spring
39A, the ease of operation of inserting the support member
35 into the hole
37 and the prevention of the rise of the support member
35 can be realized in a well-balanced manner.
[0074] With the internal combustion engine
10 according to the present embodiment, the groove
37a that engages with the ball
39C of the ball plunger
39 is formed on the inner circumferential surface of the hole
37 of the cylinder head
12. Thus, when the support member
35 is inserted into the hole
37, the ball
39C engages with the groove
37a, and the support member
35 is even less likely to rise. Therefore, the ease of installment of the support member
35 and the prevention of fretting wear, or the like, due to rising of the support member
35 can be both realized at a high level.
[0075] In the present embodiment, the groove
37a has the sloped surface
37b (see FIG.
13). Since the groove
37a has the sloped surface
37b, the ball
39C of the ball plunger
39 is unlikely to come out of the groove
37a, and the support member
35 is even less likely to rise. Therefore, it is possible to even better prevent fretting
wear, or the like, due to rising of the support member
35.
[0076] In the present embodiment, the groove
37a is a cone-shaped or circular columnar-shaped groove having the axis
13c that is inclined relative to the center line
37c of the hole
37. According to the present embodiment, the groove
37a can be machined by inserting the tool
13 such as a drill or an endmill into the hole
37 from outside the hole
37. Therefore, the groove
37a can be formed in a simple and inexpensive manner.
[0077] Note that while the groove
37a may be formed only at one point in the circumferential direction of the hole
37, it may be formed in a circumferential pattern (see the phantom line in FIG.
13). Where the groove
37a is formed only at one point in the circumferential direction of the hole
37, if the position at which the groove
37a is machined is shifted in the circumferential direction, the position at which the
support member
35 is attached in the circumferential direction may possibly be shifted. However, where
the groove
37a is formed in a circumferential pattern, the position at which the support member
35 is attached in the circumferential direction is prevented from being shifted. Therefore,
even if the machining precision of the groove
37a is relatively low, it is possible to properly machine the groove
37a. Thus, the groove
37a can be formed in a simple and inexpensive manner.
[0078] While one embodiment of the present invention has been described above, it is needless
to say that the present invention is not limited to this embodiment. Next, examples
of alternative embodiments will be described. First, an example of an alternative
embodiment employing a different configuration of the securing member will be described.
[0079] With the internal combustion engine
10 according to an alternative embodiment shown in FIG.
14, the securing member is the ball plunger
39 including the spring
39A and the spring seat
39B that are arranged inside the cylinder head
12, and the ball
39C at least a portion of which is arranged inside the hole
37. The spring
39A is a compression coil spring, wherein one end of the spring
39A is connected to the spring seat
39B and the other end thereof is connected to the ball
39C. A groove
35a that engages with the ball
39C is formed on the outer circumferential surface of the shaft portion
35A of the support member
35. Note however that the groove
35a is not always necessary and may be omitted. In the present embodiment, the ball
39C, the spring seat
39B and the spring
39A correspond to the "first contact portion", the "second contact portion" and the "elastic
portion", respectively.
[0080] Also in the present embodiment, the support member
35 can be secured inside the hole
37 by the ball plunger
39 simply by inserting the support member
35 into the hole
37. It is possible to prevent fretting wear, or the like, due to rising of the support
member
35 while maintaining the ease of installment of the support member
35. It is possible to prevent the lowering of the connecting function of the rocker arm
40. By appropriately setting the spring constant, etc., of the spring
39A, the ease of operation of inserting the support member
35 into the hole
37 and the prevention of the rising of the support member
35 can be realized in a well-balanced manner. According to the present embodiment, there
is no need to install the ball plunger
39 inside the support member
35, and it is possible to increase the degree of freedom in the position of installment
of the securing member.
[0081] As shown in FIG.
15A and FIG.
15B, with the internal combustion engine
10 according to an alternative embodiment, the securing member is a snap ring
139 fitted to the support member
35. In the present embodiment, a groove
35F is formed on the outer circumferential surface of the shaft portion
35A of the support member
35, and the snap ring
139 is fitted to the groove
35F. The groove
37a that engages with the snap ring
139 is formed on the inner circumferential surface of the hole
37 of the cylinder head
12. Note, however, that the groove
37a is not always necessary and may be omitted. When the shaft portion
35A of the support member
35 is inserted into the hole
37 of the cylinder head
12, the snap ring
139 is pressed by the inner circumferential surface of the hole
37 so as to elastically deform radially inward. In other words, the radius of the snap
ring
139 decreases. By the elastic force generated following the deformation of the snap ring
139, the support member
35 is pressed against the inner circumferential surface of the hole
37 with the snap ring
139 therebetween. Thus, the support member
35 is secured inside the hole
37. According to the present embodiment, the securing member is the snap ring
139, and therefore the securing member can be configured to be simple and compact.
[0082] As shown in FIG.
16, the snap ring
139 may be fitted to the inner circumferential surface of the hole
37 of the cylinder head
12 so that the snap ring
139 serves as the securing member for securing the support member
35. In the present embodiment, a groove
37F is formed on the inner circumferential surface of the hole
37, and the securing member is the snap ring
139 fitted into the groove
37F. The groove
35F that engages with the snap ring
139 is formed on the outer circumferential surface of the support member
35. Note, however, that the groove
35F is not always necessary and may be omitted. In the present embodiment, when the shaft
portion
35A of the support member
35 is inserted into the hole
37, the snap ring
139 elastically deforms radially outward by being pressed by the outer circumferential
surface of the support member
35. In other words, the radius of the snap ring
139 increases. By the elastic force generated following the deformation of the snap ring
139, the support member
35 is pressed against the inner circumferential surface of the hole
37 with the snap ring
139 therebetween. Thus, the support member
35 is secured inside the hole
37. Also in the present embodiment, the securing member is the snap ring
139, and therefore the securing member can be configured to be simple and compact.
[0083] As shown in FIG.
17A and FIG.
17B, with the internal combustion engine
10 according to an alternative embodiment, the securing member is a ring-shaped coil
spring
239 wound around the support member
35. In the present embodiment, the groove
35F is formed on the outer circumferential surface of the shaft portion
35A of the support member
35, and the ring-shaped coil spring
239 is fitted to the groove
35F. The groove
37a that engages with the coil spring
239 is formed on the inner circumferential surface of the hole
37 of the cylinder head
12. Note, however, that the groove
37a is not always necessary and may be omitted. When the shaft portion
35A of the support member
35 is inserted into the hole
37, the ring-shaped coil spring
239 elastically deforms radially inward by being pressed by the inner circumferential
surface of the hole
37. By the elastic force generated following the deformation of the coil spring
239, the support member
35 is pressed against the inner circumferential surface of the hole
37 with the coil spring
239 therebetween. Thus, the support member
35 is secured inside the hole
37. According to the present embodiment, the securing member is the ring-shaped coil
spring
239, and therefore the securing member can be configured to be simple and compact.
[0084] As shown in FIG.
18, the ring-shaped coil spring
239 may be fitted to the inner circumferential surface of the hole
37 so that the coil spring
239 serves as the securing member for securing the support member
35. In the present embodiment, the groove
37F is formed on the inner circumferential surface of the hole
37, and the securing member is the ring-shaped coil spring
239 fitted to the groove
37F. The groove
35F that engages with the coil spring
239 is formed on the outer circumferential surface of the support member
35. Note, however, that the groove
35F is not always necessary and may be omitted. In the present embodiment, when the shaft
portion
35A of the support member
35 is inserted into the hole
37, the ring-shaped coil spring
239 elastically deforms radially outward by being pressed by the outer circumferential
surface of the support member
35. By the elastic force generated following the deformation of the coil spring
239, the support member
35 is pressed against the inner circumferential surface of the hole
37 with the coil spring
239 therebetween. Thus, the support member
35 is secured inside the hole
37. Also in the present embodiment, the securing member is the ring-shaped coil spring
239, and therefore the securing member can be configured to be simple and compact.
[0085] As shown in FIG.
19, the securing member may be a leaf spring
339 secured to the edge of the hole
37 of the cylinder head
12. Herein, the leaf spring
339 is secured to the cylinder head
12 by a pin
340. The leaf spring
339 is formed with a hole
339d through which the support member
35 passes. The edge of the hole
339d of the leaf spring
339 is a first contact portion
339a that contacts the support member
35. A portion of the leaf spring
339 that is supported by the pin
340 is a second contact portion
339b that contacts the cylinder head
12 with the pin
340 therebetween. A portion between the first contact portion
339a and the second contact portion
339b is an elastic portion
339c. According to the present embodiment, the securing member is the leaf spring
339, and therefore the securing member can be configured to be simple.
[0086] In the embodiment described above, the first arm
41 is configured so as not to be in contact with the cam
21A,
23A. In the embodiment described above, the valve
20,
22 is brought to the inoperative state by switching the first arm
41 and the second arm
42 of the rocker arm
40 to the non-connected state. However, the first arm
41 may have a contact portion that contacts the cam
21A,
23A after the second arm
42 starts pivoting as the roller
43 is pushed by the cam
21A,
23A. In such a case, it is possible to change the timing with which the valve
20,
22 is opened and closed by switching the first arm
41 and the second arm
42 to the non-connected state. Thus, it is possible to change the period in which the
valve
20,
22 is open. For example, by elongating the period in which the valve
20,
22 is open when the speed of the internal combustion engine
10 is high, it is possible to improve the performance at a high engine speed.
[0087] In the embodiment described above, the internal combustion engine
10 is a multi-cylinder engine. However, the internal combustion engine
10 may be a single-cylinder engine with which it is possible to change the timing with
which the valve
20,
22 is opened/closed.
[0088] In the embodiment described above, the internal combustion engine
10 includes a variable valve mechanism. That is, the rocker arm
40 includes the first arm
41, and the second arm
42 pivotally supported on the first arm
41. The internal combustion engine
10 includes the connection switch pin
66 as a connecting mechanism that removably connects the first arm
41 and the second arm
42. However, the internal combustion engine
10 may not include a variable valve mechanism. The connecting mechanism may be omitted.
The second arm
42 may be formed integral with the first arm
41, and the rocker arm
40 may be a single-piece member. The internal combustion engine
10 may be unable to bring the valve
20,
22 to the inoperative state, and may be configured unable to change the timing with
which the valve
20,
22 is opened/closed.
[0089] The terms and expressions used herein are used for explanation purposes and should
not be construed as being restrictive. It should be appreciated that the terms and
expressions used herein do not eliminate any equivalents of features illustrated and
mentioned herein, but include various modifications falling within the claimed scope
of the present invention. The present invention may be embodied in many different
forms. The present disclosure is to be considered as providing examples of the principles
of the invention. These examples are described herein with the understanding that
such examples are not intended to limit the present invention to preferred embodiments
described herein and/or illustrated herein. Hence, the present invention is not limited
to the preferred embodiments described herein. The present invention includes any
and all preferred embodiments including equivalent elements, modifications, omissions,
combinations, adaptations and/or alterations as would be appreciated by those skilled
in the art on the basis of the present disclosure. The limitations in the claims are
to be interpreted broadly based on the language included in the claims and not limited
to examples described in the present specification or during the prosecution of the
application.
REFERENCE SIGNS LIST
[0090] 5: Automobile (vehicle), 10: Internal combustion engine, 12: Cylinder head (cylinder
member), 14: Exhaust port, 16: Intake port, 20: Exhaust valve, 21: Exhaust cam shaft,
21A: Exhaust cam, 22: Intake valve, 23: Intake cam shaft, 23A: Intake cam, 35: Support
member, 37: Hole, 37a: Groove, 37b: Sloped surface, 39: Ball plunger (plunger mechanism),
39A: Spring, 39C: Ball (presser), 40: Rocker arm, 41: First arm, 41C: Abutting plate
(abutting portion), 41S: Supported portion, 42: Second arm, 43: Roller (pressed portion),
66: Connection switch pin (connecting mechanism), 139: Snap ring, 239: Coil spring,
339: Leaf spring